Alpha Center proposes to conduct a two-day conference to bring together individuals and representatives of organizations who use, analyze, collect and maintain the data that would be needed to conduct studies of competition and its effects in the health care marketplace. It will contain presentations and workshops on what analyses of the effects of health care competition most need to be addressed by researchers, policy analysts, antitrust analysts, providers, and purchasers of health care; what data are available to produce these analyses, and whether data could be shared and linked in a manner that would benefit all who are interested in producing better, more meaningful studies of competition in health care. This conference would lay out the reasons why studies of the effects of competition are increasingly important as the health care market consolidates and evolves. It would then describe the research to date examining the effects of competition among hospitals, HMOs, and physicians on price, quality, consumer satisfaction, and access to care, noting in particular gaps in the data and methodologies. Several case studies of how researchers who work with proprietary data can share their databases with others will be presented. In addition, there will be small break-out sessions where antitrust analysts, economic analysts, providers, purchasers and policy analysts lay out research questions of highest priority to them and the available data elements that could be used to address those questions. Other sessions will include the role of the government in collecting, disseminating and linking databases that can be used to measure competition and its effects in health care markets, and next steps to help improve both data and methods.